Is there any negative effect of Revo Uninstaller pro?

In my computer there is two software running those I want to uninstall. I think I need to use a program like Revo Uninstaller pro. I cannot uninstall the software or delete them from program files because they are saying the program in use or ask password. I have never set password for them. Will Revo Uninstaller pro will work? Will it make any negative impact on my computer?
